Fix imageSourceURL() for WebGL elements.

Source/core/html/canvas/WebGLRenderingContextBase.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 330 matching lines @@
 
     void removeSharedObject(WebGLSharedObject*);
     void removeContextObject(WebGLContextObject*);
 
     unsigned maxVertexAttribs() const { return m_maxVertexAttribs; }
 
     // ActiveDOMObject notifications
     virtual bool hasPendingActivity() const OVERRIDE;
     virtual void stop() OVERRIDE;
 
+    void setSavingImage(bool isSaving) { m_savingImage = isSaving; }
 protected:
     friend class WebGLDrawBuffers;
     friend class WebGLFramebuffer;
     friend class WebGLObject;
     friend class OESVertexArrayObject;
     friend class WebGLDebugShaders;
     friend class WebGLCompressedTextureATC;
     friend class WebGLCompressedTextureETC1;
     friend class WebGLCompressedTexturePVRTC;
     friend class WebGLCompressedTextureS3TC;
@@ skipping 167 matching lines @@
     int m_numGLErrorsToConsoleAllowed;
 
     bool m_multisamplingAllowed;
     bool m_multisamplingObserverRegistered;
 
     GLuint m_onePlusMaxEnabledAttribIndex;
     unsigned long m_onePlusMaxNonDefaultTextureUnit;
 
     OwnPtr<Extensions3DUtil> m_extensionsUtil;
 
+    bool m_savingImage;
+
     enum ExtensionFlags {
         ApprovedExtension               = 0x00,
         // Extension that is behind the draft extensions runtime flag:
         DraftExtension                  = 0x01,
         // Extension that is still in draft state, but has been selectively enabled by default under a prefix. Do not use
         // this for enabling new draft extensions; use the DraftExtension flag instead, and do not use vendor prefixes:
         EnabledDraftExtension           = 0x04,
     };
 
     class ExtensionTracker {
@@ skipping 354 matching lines @@
     // If the vector is empty, return the maximum allowed active context number.
     static size_t oldestContextIndex();
     static IntSize oldestContextSize();
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace WebCore
 
 #endif // WebGLRenderingContextBase_h